GPS Week Number Rollover (WNRO)

Hello everybody,
had some trouble with my RC, Defy+, BTQ818XT-Setup recently. Always worked fine since I got the GPS a year ago, as well as end of march, when I had my first outing this year. Now, end of april I had my second outing and I couldn't get to run it at all, well almost: 5 Laps it did, but later didn't measured one more Lap. I realized that my Smartphone would shut down before or when I finished my first Lap, as I could see the "Motorola"-Sign on the Screen. After my Stints I had to start the phone again.

I supposed it was a hardware-failure, but today I found a firmware-update for my GPS-device, mentioning a "GPS Week Number Rollover (WNRO) -Issue". Here's what QStarz states:


Qstarz statement for the April 2019 GPS Week Number Rollover issue

Taipei, Taiwan, April 03, 2019

Regarding the GPS Week Number Rollover (WNRO) issue, the GPS date and time are calculated based on the number of week during the development of the GPS system, and the week number of the chip plan can only be calculated up to 1024 weeks, or about 19.7 years. After every 1024 weeks, this counter is "reset" to zero and the GPS time starts counting again. The first GPS week rollover occurred in August 1999. The second time will occur on April 6, 2019.
Click here to read the US Department of Homeland Security’s memorandum about the upcoming Global Positioning System Week Number Rollover Event.

The affected product will display the wrong date and time when the GPS week is rollover. However, the positioning accuracy is not affected. The wrong time will affect the computing and other functions of Qstarz's PC software.

Therefore Qstarz is devoted ourselves to test and correct our products with the most strict attitude. All Qstarz GNSS products such as LT-6000S [GNSS], BL-1000GT and BL-1000ST will not be affected by the GPS week rollover. For affected Qstarz GPS models, Qstarz will one after another release corresponding model’s new firmware to solve the issue.

The following are the affected Qstarz GPS product models:

Selling Models:


Discontinued Models:



Now I don't know if this really has smtgh. to do with my issue, as my device was able to take these 5 Laps and QStarz mentiones that GPS-Locating is not affected. Though I had issues with my device before when system-time and date was not set up properly in the phone, so I wonder if the incorrect date+time on the GPS-Device is critcal as well. Maybe someone with more real-depth knowledge can give a quote about that.

For everybody else this might be a hint if your device has unexplainable issues since april. I updated my device and will make another test soon. Here's the link to the firmware per model-selection:


  • Dear aol,
    sorry, heaven't seen that before sorry, otherwhise I wouldn't have posted it.

    But as we already talk about it ;) : You mention aswell that there is no problem with wrong Date, regarding laptiming (except date of your recording, sure), but I've encountered issues before, when the system-time from my phone wasn't setup right. Could it be possible, that this leads into the App or my device crashing or could it just have been coincidence and I have another problem (hardware-failure as I mentioned before)?
    Sorry to bug on this, it's just that I like my Defy+ device, as it is small, robust and has been good enough for my purposes (only time my laps). As I do Supermoto-Racing on small Kart-tracks, incl. Offroad-Sections, I really want a robust device, as crashes do happen sometimes. The Defy is excellent for that purpose.

    Thanks for a hint in advance.
  • edited July 2019
    @Connander, I think the hardware shutdown (or crash) is unrelated to the WNRO issue. A bug in RaceChrono will crash the app (hypothetically: unexpected input or date from GPS), but never reboot the system. If your phone reboots there's something wrong with the system software/firmware or a hardware failure (like something caused by vibrations in long run).
  • Is there any kind of log I could look for? I would love to be sure that it's the hardware, as I just loved the Defy, as it's super small and super robust.
Sign In or Register to comment.